Hey ikaros,
I have 3 solutions to your problems and which one you choose is entirely up to you. Of course CCNA is considered a very important certification in the networking field.
On to the solutions:
1) Retake the test
2) Sit for the 642-831 CIT Cisco Internetwork Troubleshooting exam which is the simplest in the CCNP career path an will get your CCNA valid again
3) Wait until you find a cisco network engineer job and note in your cv and interview that you were CCNA and could sit for the exam again if the company requires it.
Since you got the CCNA 4 years ago I believe that sitting again for the same exam is not a bad idea, as it has changed a bit.

On to the solutions:
1) Retake the test
2) Sit for the 642-831 CIT Cisco Internetwork Troubleshooting exam which is the simplest in the CCNP career path an will get your CCNA valid again
3) Wait until you find a cisco network engineer job and note in your cv and interview that you were CCNA and could sit for the exam again if the company requires it.
Since you got the CCNA 4 years ago I believe that sitting again for the same exam is not a bad idea, as it has changed a bit.

You've been a great help, and I'm more inclined towards solution 2 or 1. Though when I discussed my dilemma with friends and colleagues from work they all suggested a forth solution.

They all said “accept the fact that you are a software engineer and it is extremely difficult if not impossible for a company to see you otherwise. If you’re not happy with your current job start looking for another one you have a lot more chances as a software engineer”

I’m thinking maybe they’re right, anyway I’ll give it one more shot on solution 2 or 1 as not to loose contact with networks and at the same time start job hunting as a software engineer.